Cod sursa(job #3151017)

Utilizator ukeremKerem U ukerem Data 19 septembrie 2023 13:03:25
Problema Arbori indexati binar Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.34 kb
#include <fstream>
#include <vector>
using namespace std;
int N;
vector<int> bit(150002,0),v;
ifstream in("aib.in");
ofstream out("aib.out");
void update(int i,int val)
{
    while(i<=N)
    {
        bit[i]+=val;
        i+= i & -i;
    }
}
int prefixSum(int i)
{
    int sum=0;
    while(i>0)
    {
        sum+=bit[i];
        i-= i & -i;
    }
    return sum;
}
int rangeSum(int i, int j)
{
    return prefixSum(j) - prefixSum(i-1);
}
int lbound(int ca)
{
    int l=1,r=N,mid=-1,aux;
    while(l<r)
    {
        mid=(l+r)/2;
        aux=prefixSum(mid);
        if(aux>=ca)
            r=mid;
        else
            l=mid+1;
    }
    return l;
}
int main()
{
    int x,m;
    in>>N>>m;
    v.push_back(0);
    for(int i=1;i<=N;i++)
    {
        in>>x;
        v.push_back(x);
        update(i,x);
    }
    int op,a,b;
    for(int i=0;i<m;i++)
    {
        in>>op;
        if(op==0)
        {
            in>>a>>b;
            update(a,b);
        }
        else if(op==1)
        {
            in>>a>>b;
            out<<rangeSum(a,b)<<'\n';
        }
        else if(op==2)
        {
            in>>a;
            int aux=lbound(a);
            if(rangeSum(1,aux)!=a)
                out<<-1<<'\n';
            else
                out<<aux<<'\n';
        }
    }
    return 0;
}